It is known to increase the resistance of wood against weather conditions by a coating of lacquer and color paints. Dimensional changes of the wood, for example caused by swelling and shrinkage due to water absorption or release, caused by external humidity changes, nevertheless lead to peeling of such paints.
It is further known, to protect the optical appearance and the resistance of wood against harmful microorganisms, for example blueing fungi or white rot, brown rot and soft rot, by an impregnation with a mixture of arsenic, ionic copper and chromium VI.
Such wood preservatives are disadvantageous for the reason that at least chromium and arsenic are harmful and toxic for the environment. Even copper complexes and boron compounds are now seen as critical under the same aspects.
Furthermore, water-soluble wood preservatives are known which comprise a quaternary ammonium compound such as for example benzalkonium chloride. Such wood preservatives are disadvantageous as they are deposited only in the upper layers of the wood due to their immediate bonding to wood.
Further biocidal actives are 3-iodo-2-propynyl butyl carbamate (IPBC) or triazoles (propiconazole, tebuconazole).
The known organic wood preservatives are used in the application categories 1, 2 and 3 according to DIN EN 351 and do not lead to hydrophobing the wood so that the tendency of the wood to absorb water and therewith the dimensional stability remain unchanged.
To reduce the water absorption of wood, essentially compounds based on oils, fats and waxes (paraffins and silicones) were used.
Known wood preservatives, which are used for hydrophobing and which have a content of silicon compounds, are known too. Thus, JP 2002-348567 A describes wood preservatives, which consist of a mixture of different alkoxysilanes, including amino group containing alkoxysilanes and boric acid.
U.S. Pat. No. 6,294,608 discloses aqueous emulsions for treating mineral construction materials and wood with a mixture of silanes which have alkyl and alkoxy groups or aminoalkyl groups. Polysiloxane compounds are not disclosed.
EP 0716127 discloses polyorganosiloxanes as well as aqueous mixtures thereof, which are particularly used for hydrophobing surfaces, e.g. in the impregnation of leather and textiles made from natural and/or artificial materials and in the field of organic and mineral construction materials as well as building protection.
EP 0716128 discloses aminoalkyl alkoxysilanes which can be used among others for hydrophobing cellulose products or as additives for paints and lacquers. Polyorganosiloxanes are not disclosed therein.
US 2002/0026881 describes a composition for hydrophobing surfaces which contains silicone among others.
U.S. Pat. No. 4,757,106 discloses the combination of aminoorganosiloxanes with basic nitrogen contents of >0.5% with siloxanes with a molecular weight of >620 g/mol in substantially solvent-free formulations as equipment for mineral substrates.
DE 3447636 discloses the combination of aminoorganosiloxanes with basic nitrogen contents of >0.5% with a second amino siloxane with basic nitrogen content of 0 to 0.5% and optionally a siloxane with molar masses <600 g/mol in the presence of solvents.
EP 0621115 and DE 4241727 disclose the combination of aminoorganosiloxanes with basic nitrogen contents of >0.5% with water-repellent agents, e.g. siloxanes, optionally in the presence of a second compound with basic nitrogen in contents of 0 to 0.5% for the treatment of wood. DE 10 2004 036918 proposes the use of aminoorganosiloxanes in wood preservatives. The siloxanes shall have a molecular weight of 500 to 500,000 g/mol and the degree of substitution of the siloxane units with amino groups shall be up to 50%.
DE 4202320 describes the impregnation of wood with a non-functionalized polydimethylsiloxane by using supercritical carbon dioxide as a carrier medium. The disadvantage of this proposal is that the non-functionalized polydimethylsiloxane can be leached from the wood.
EP 680810 describes the modification of wood by acetylation with acetic anhydride at elevated temperatures. The disadvantage of this procedure is an insufficient reduction of the water uptake of the modified wood.